Slides suddenly changing order

[jshepnz]

I'm using PP 2003 with Windows 7 64.
I was sent a slide show with a composite music file for full length of presentation The timing of the slides really needed some editing. However I had to ensure the correct slides were displayed for the length of that part of the music track that was appropriate for those slides. Knowing that to check any editing you have to play the slide show from the beginning (to initiate music) it can be very time consuming. So I split the single sound track to its component pieces with sound editing software and then set the timing as required so that the number of slides matched the length of the music. This way I only had to play through the section until my editing was correct. However a most strange problem occurred. As I was going through setting the slide transition timings suddenly the slide I'm setting will move to a different place in the slide show. I think it may be to do with the link to the original file that was sent to me. I did remove the sound icon before I did my own section by section sound. Most strange and I'm at a loss what could be causing this ... Any one any ideas?